introduce incremental md5 digester

Signed-off-by: Michael Krelin <hacker@klever.net>

2 files changed, 51 insertions, 0 deletions

diff --git a/src/eyetil.cc b/src/eyetil.cc
index 7669cb6..57ae607 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -57,32 +57,46 @@ std::string binary_t::hex() const {
 	int rc = snprintf(t,sizeof(t),"%02x",*i);
 	assert(rc<sizeof(t));
 	rv += t;
     }
     return rv;
 }
 
 binary_t binary_t::md5() const {
     binary_t rv(MD5_DIGEST_LENGTH);
     if(!MD5(
 		(const unsigned char*)&(front()),size(),
 		(unsigned char*)&(rv.front()) ))
 	throw std::runtime_error("failed to md5()");
     return rv;
 }
 
+void md5_digester::init() {
+    if(!MD5_Init(&ctx)) throw std::runtime_error("failed to MD5_Init()");
+}
+void md5_digester::update(const void *d,size_t l) {
+    if(!MD5_Update(&ctx,d,l)) throw std::runtime_error("failed to MD5_Update()");
+}
+binary_t md5_digester::final() {
+    binary_t rv(MD5_DIGEST_LENGTH);
+    if(!MD5_Final((unsigned char*)&(rv.front()), &ctx))
+	throw std::runtime_error("failed to MD5_Final()");
+    return rv;
+}
+
+
 static void make_path_for_template(const std::string& p,mode_t m) {
     struct stat st;
     std::string pp;
     for(std::string::size_type sl=p.find('/',1);
 	    sl!=std::string::npos;
 	    sl=p.find('/',sl+1)) {
 	if(stat( (pp=p.substr(0,sl)).c_str() ,&st)
 		|| !S_ISDIR(st.st_mode)) {
 	    if(mkdir(pp.c_str(),m))
 		throw std::runtime_error("failed to mkdir()");
 	}
     }
 }
 
 tmpdir_t::tmpdir_t(const std::string& dt) : dir(dt) {
     make_path_for_template(dt,0777);
diff --git a/src/eyetil.h b/src/eyetil.h
index d946e71..eff2c43 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -1,39 +1,76 @@
 #ifndef __EYETIL_H
 #define __EYETIL_H
 
 #include <vector>
 #include <string>
 #include <archive.h>
 #include <archive_entry.h>
+#include "openssl/md5.h"
 
 class binary_t : public std::vector<unsigned char> {
     public:
 	binary_t() { }
 	binary_t(size_type  n) : std::vector<unsigned char>(n) { }
 	binary_t(const std::string& h) { from_hex(h); }
 	binary_t(const void *d,size_t s) { from_data(d,s); }
 
 	binary_t& from_hex(const std::string& h);
 	binary_t& from_data(const void *d,size_t s);
 	binary_t& make_nonce();
 
 	std::string hex() const;
 	binary_t md5() const;
 };
 
+struct md5_digester {
+    MD5_CTX ctx;
+    md5_digester() { init(); }
+
+    void init();
+    void update(const void *d,size_t l);
+    binary_t final();
+
+    template<typename T>
+    void update(const T& x) { update(&x,sizeof(x)); }
+
+    template<typename T>
+    struct update_iterator : public std::iterator<std::output_iterator_tag,T,void,T*,T&> {
+	md5_digester *d;
+	update_iterator(md5_digester *d_) : d(d_) { }
+	update_iterator(const update_iterator& x) : d(x.d) { }
+
+	update_iterator& operator*() { return *this; }
+	update_iterator& operator++() { return *this; }
+	update_iterator& operator++(int) { return *this; }
+
+	update_iterator& operator=(const T& x) {
+	    d->update(x); return *this;
+	}
+    };
+
+    template<typename T>
+    update_iterator<T> updater() {
+	return update_iterator<T>(this);
+    }
+
+};
+template<> inline void md5_digester::update<binary_t>(const binary_t& x) {
+    update((const unsigned char*)&(x.front()),x.size());
+}
+
 class tmpdir_t {
     public:
 	std::string dir;
 
 	tmpdir_t(const std::string& dt);
 	~tmpdir_t();
 
 	std::string get_file(const std::string& f);
 };
 
 class tarchive_t {
     public:
 	struct archive *a;
 	struct archive_entry *e;
 
 	tarchive_t(void *p,size_t s);